Move Python bindings to use pybind11

CHANGELOG.md

cmake/NektarCommon.cmake

cmake/ThirdPartyPython.cmake

docker/nekmesh/Dockerfile

docker/nektar-env/Dockerfile

docker/nektar-env/README.md

docker/nektar-env/bookworm_full_packages.txt

docker/nektar-env/bullseye_full_packages.txt

docker/nektar-env/fedora35_default_packages.txt

docker/nektar-env/fedora35_full_packages.txt

docker/nektar-env/fedora36_default_packages.txt

docker/nektar-env/fedora36_full_packages.txt

docker/nektar-env/focal_full_packages.txt

docker/nektar-env/jammy_full_packages.txt

docker/nektar-env/noble_full_packages.txt

docker/nektar/Dockerfile

docker/packaging/Dockerfile-debian-bookworm

docker/packaging/Dockerfile-debian-bullseye

docker/packaging/Dockerfile-debian-unstable

docker/packaging/Dockerfile-ubuntu-focal